First Report of Neoerysiphe galeopsidis on Althaea rosea

Hollyhock (Althaea rosea) is a common ornamental plant in northeast China, as well as a medicinal plant used to treat enteritis and dysentery. In 2004, a significant outbreak of powdery mildew disease occurred. In September, infected leaves of Althaea rosea were collected in Changchun, northeast China. Morphological characteristics of ascomata were observed using both light and scanning electron microscopy. Ascomata were gregarious or subscattered, 80-150 µm in diameter, cells obscure, irregularly shaped; appendages were numerous, in the lower half of the ascomata, often forming a dense felt around the fruit bodies, mycelioid, interlaced with the mycelium and with each other, septate, thin-walled, smooth, hyaline to brown, usually simple, rarely irregularly branched, 0.25-1.2 times as long as the ascomata diam, often shorter than the ascomata diam, 4.5-7.9 µm wide, rarely exceeding; asci 6-15, sessile or shortly stalked, 42-79x22-40 µm. Ascospores were not developed before overwintering, with asci always immature in the current season. The diseased plant specimens are deposited in the Mycological Institute Herbarium of Jilin Agricultural University, P.R. China (accession number 04036) and the Mie University Mycological Herbarium, Japan (accession number 3389).

The characteristic of the fungus described above is similar to the fungus found on Galeopsis bifida and identified as Neoerysiphe galeopsidis. Braun (1999) introduced the new genus Neoerysiphe with Erysiphe galeopsidis as the type species. Zheng & Yu (1987) reported E. galeopsidis on G. bifida, Galeopsis spp., Lagopsis supina, Lamium album, L. barbatum and Lycopus spp. However there is no record of this fungus on Althaea spp. in China or elsewhere (Braun, 1987). The ITS sequence of this fungus was compared with that of Chelonopsis moschata (Mori et al. 2000; Acc. No. AB022368) and shown to share sequence similarity of 99.8%. This is the first report of N. galeopsidis on Althaea rosea.